When dentists polish the proximal surface of a tooth of a patient or a filling in the proximal cavity for odontotherapy in a state where polishing instruments such as points, bars, disks, etc. are attached to a dental hand piece, they generally use a dental polishing strip, if there is a possibility that the teeth adjacent to the tooth to be treated may be damaged. The dental polishing strip has generally compacted abrasive grains to form a polishing surface on one side of a narrow foil-like substrate which is 2 to 5 mm in width, 120 to 180 mm in length and under 0.09 mm in thickness. For polishing, the strip is gradually inserted in the interdental space to allow the polishing surface to come in contact with the proximal surface of a tooth to be polished or a filling in the proximal cavity. Then, the strip is reciprocated vertically with respect to the longitudinal direction of the tooth. The materials of dental polishing strips are generally separated into two types, one the strips made of synthetic resins and the other the type being made of metals.
Referring to the dental polishing type being made of synthetic resins, polishing abrasive grains are compacted on a synthetic resin substrate with the use of adhesives to form a polishing surface. However, due to the fact that they are rich in flexibility but poor in strength, they have the disadvantages that the abrasive grains separate off, or the substrate per se extends with a drop of cutting force, during polishing. Furthermore, since they are less resistant to heat, they cannot be sterilized by heating for repeated use. Thus, they are used only once and should be thrown away.
On the other hand, the dental polishing strips made of metals are of three types. Referring to the first type, polishing abrasive grains are compacted on a substrate formed of stainless steel or steel to form a polishing surface. According to the second type, a number of small holes are formed in a substrate without recourse to any abrasive grains to form a polishing surface. According to the third type, a substrate is formed like a file on its surface to form a polishing surface. In the case of the first type strip, the substrate per se does not extend, and is fixedly provided with the abrasive grains, so that only slight separation thereof takes place, and high cutting force is maintained. All the first, second and third type polishing strips undergo neither tarnish nor deformation due to cleaning and heating sterilization, and so have excellent durability. Thus, the metal-made polishing strips can repeatedly be used by cleaning and heating sterilization.
However, when the metal-made dental polishing strips are repeatedly used to polish the proximal surfaces of teeth or fillings in the proximal cavity, polishing occurs along the curved planes of teeth or fillings, so that they are curved, as illustrated in FIG. 3. For that reason, difficulty is involved in inserting them into the interdentium for re-use. Furthermore, even upon sterilized by heating, they give a patient an unsanitary impression that they are much used. In addition, the metal-made strips deform to varied forms, and are so hard to arrange at the time of storage. It is thus difficult to select a proper one of the desired roughness from several types of polishing strips that are irregularly arranged. It is possible to solve the problems resulting from the appearance and manipulation of the metal-made strips by manually putting the curved strips to a straight state before use. However, this work is very troublesome to dentists. Alternatively, if the metal-made strips are substituted with new ones while the old ones are still useable, this solution suffers from an economical problem.